Optimization of Titanium Aluminium Nitride Thin film Coatings for Solar Absorptance

Abstract

Improving the properties of the solar selective coating on the receiver represents one of the best opportunities for improving the efficiency of solar thermal receiver tubes. Optimization of titanium aluminium nitride thinfilm coatings to enhance the solar absorptance (α) and thermal emittance (ε). Design of experiments (DOE) approach is used for optimization of the process parameters for deposition of titanium aluminium thinfilm coatings with absorptance and emittance as the response function. Improved selective absorber thinfilm coatings for absorption of radiation should maintain high coefficient of absorption in the solar spectrum (UV VIS NIR) however lower emittance within the infrared spectrum. The optical properties of those thinfilms were studied through optical coefficient measurements and it had been found that the titanium and aluminium has high contribution towards coefficient of absorption and emittance that affects the optical performance. The results indicate that titanium aluminium nitride thinfilms has an absorptance of 0.90 with a deposition parameters (a) aluminium RF sputtering power of 180 W, (b) titanium DC power of 60W, (c) argon to nitrogen gas ration of 5:10 sccm and (c) temperature of the 200 degrees  and emittance of 0.22 with a deposition parameters (a) aluminium RF sputtering power of 180 W, (b) titanium DC power of 60W, (c) argon to nitrogen gas ration of 5:10 sccm and (c) temperature of the 200 degrees  and emittance of 0.22 with a deposition parameters (a) aluminium RF sputtering power of 60 W, (b) titanium DC power of 60W, (c) argon to nitrogen gas ration of 15:30 sccm and (c) temperature of the 200 degrees.